I coded a jquery script that scrolls links inside a span when mouse pointer is over, and stops at mouseout.
http://jsfiddle.net/trustweb/Xvqfr/
This is a working solution but if you check CPU performances you notice how heavy it is.
Does exist a lighter solution?
If you reduce the timer interval (8ms) your performace would be better.
At the same time you should to avoid to use find method multiple times in the scrollText() method.
See demo: http://jsfiddle.net/f8sap/2/